CHAPTER 65

• Adenoviruses can cause diseases like cold symptoms (rhinitis), sore throat (pharyngitis), inflamed tonsils (tonsillitis), and croup (laryngotracheobronchitis)
• Adenoviruses


  Viruses characterized by their icosahedral shape, nonenveloped structure, and double-stranded linear DNA genome
• Adenovirus serotypes


  • 52 serotypes described so far
• Adenoviral species


  • A through G
• Adenoviruses


  • Can lead to severe and acute respiratory disease, particularly in new military recruits and crowded settings
• Adenovirus type 14


  Notable for its ability to cause illness in individuals of all ages, associated with outbreaks of respiratory illness, including severe pneumonia
• Diagnostic methods for adenovirus infection


  • Cell culture
  • Immunofluorescence assay (IFA)
  • Enzyme immunoassay (EIA)
  • Rapid cell culture
• Adenovirus-infected cells in cell culture


  Often exhibit a characteristic grape-like cytopathic effect (CPE)
• Adenoviruses are important pathogens that can cause a range of respiratory and gastrointestinal illnesses, particularly in vulnerable populations such as military recruits and individuals living in crowded environments
• Hepatitis B Virus (HBV) is a DNA virus that primarily infects the liver, causing hepatitis, and is transmitted through contact with infected blood, semen, or other body fluids during sexual activity
• Hepatitis C Virus (HCV) is an RNA virus that primarily affects the liver, leading to hepatitis, and is usually transmitted through exposure to infected blood, though sexual transmission is less common than with HBV
• Herpes Simplex Virus (HSV)-1 and HSV-2 are DNA viruses that cause oral and genital herpes, respectively, and are transmitted through direct contact with mucosal surfaces or skin lesions during sexual activity
• Human Papillomavirus (HPV) is a DNA virus with numerous genotypes, some of which are sexually transmitted, and can cause genital warts and is associated with various cancers, including cervical, anal, penile, and oropharyngeal cancers
• Human Immunodeficiency Virus (HIV) is an RNA virus that targets the immune system, specifically CD4+ T cells, and is transmitted through sexual contact, sharing needles, or from mother to child during childbirth or breastfeeding
• Human T-Lymphotropic Virus (HTLV) is an RNA retrovirus that primarily infects T lymphocytes and is transmitted through sexual contact, breastfeeding, and sharing needles, and can lead to adult T-cell leukemia/lymphoma (ATL) and HTLV-associated myelopathy/tropical spastic paraparesis (HAM/TSP)
• Measles is caused by the measles virus (paramyxovirus) and typically presents with a characteristic rash that starts on the face and spreads to the trunk and extremities, along with symptoms such as fever, cough, runny nose, and conjunctivitis
• Scarlet fever is caused by group A Streptococcus bacteria, usually Streptococcus pyogenes, and the rash of scarlet fever is characterized by a fine, sandpaper-like texture and typically appears after the onset of symptoms such as sore throat, fever, headache, and swollen lymph nodes
• Rubella is caused by the rubella virus (a togavirus) and the rash of rubella is typically mild and starts on the face before spreading to the trunk and extremities, and other symptoms may include low-grade fever, swollen lymph nodes, and malaise
• Fifth disease is caused by parvovirus B19 and the rash of the fifth disease is characterized by bright red cheeks, giving the appearance of "slapped cheeks," followed by a lace-like rash on the trunk and extremities, and it is often preceded by symptoms such as fever, headache, and mild cold-like symptoms
• Roseola infantum is caused by human herpesvirus 6 (HHV-6) and sometimes human herpesvirus 7 (HHV-7), and the rash of roseola typically appears after several days of high fever, resolving once the fever breaks, and the rash is often pinkish-red and may be accompanied by mild symptoms such as runny nose, cough, and irritability
• Erythema infectiosum (Fifth Disease)


  • Caused by parvovirus B19
  • Rash characterized by bright red cheeks, giving the appearance of "slapped cheeks," followed by a lace-like rash on the trunk and extremities
  • Often preceded by symptoms such as fever, headache, and mild cold-like symptoms
• Roseola Infantum


  • Caused by human herpesvirus 6 (HHV-6) and sometimes human herpesvirus 7 (HHV-7)
  • Rash typically appears after several days of high fever, resolving once the fever breaks
  • Rash is often pinkish-red and may be accompanied by mild symptoms such as runny nose, cough, and irritability
• Exanthematous diseases in children are often viral and can range from mild and self-limiting to more severe and potentially life-threatening in rare cases
• Proper diagnosis and management, including supportive care and symptomatic treatment, are important for ensuring the well-being of affected children
• Rotavirus


  • A leading cause of severe diarrhea in infants and young children worldwide
  • Highly contagious and spreads through the fecal-oral route, often in daycare centers and schools
  • Rotavirus vaccines are available and have significantly reduced the incidence of severe rotavirus gastroenteritis
• Adenovirus (Serotypes 40 and 41)


  • Certain serotypes, particularly 40 and 41, are associated with gastroenteritis, especially in children
  • Adenovirus gastroenteritis typically presents with diarrhea, abdominal pain, and occasionally vomiting
• Caliciviruses


  • Include norovirus and sapovirus, members of the Caliciviridae family
  • Norovirus is the most common cause of acute gastroenteritis in all age groups, including children, and is notorious for causing outbreaks in settings such as schools, cruise ships, and nursing homes
• Norovirus


  • Highly contagious and spreads easily in crowded or enclosed environments
  • Causes symptoms such as nausea, vomiting, diarrhea, and abdominal cramps, often leading to outbreaks in communities and healthcare facilities
• Sapovirus


  • Causes acute gastroenteritis characterized by vomiting, diarrhea, abdominal pain, and sometimes fever
  • Less common than norovirus but can still contribute to cases of viral gastroenteritis, especially in children
• Astrovirus


  • A common cause of viral gastroenteritis, particularly in young children
  • Typically presents with symptoms such as diarrhea, vomiting, and abdominal discomfort, although it tends to be milder compared to norovirus and rotavirus infections
• Nausea


  Norovirus infection often begins with a feeling of nausea, which can range from mild discomfort to severe queasiness. Nausea may be persistent and may precede other symptoms.
• Abdominal Cramps


  Many individuals infected with norovirus experience abdominal cramps or stomach pain. These cramps can be mild to severe and may come and go throughout the illness.
• Vomiting


  Vomiting is a hallmark symptom of norovirus infection, and it can be frequent and intense. In some cases, vomiting may be the predominant symptom, especially in the early stages of the illness.
• Watery Diarrhea


  Norovirus infection often leads to watery diarrhea, which can be profuse and frequent. This diarrhea may be accompanied by urgency and can result in dehydration if not adequately managed.
• These symptoms typically develop within 12 to 48 hours after exposure to the virus and can last for 1 to 3 days. Norovirus infections are highly contagious, and the virus can spread easily through contaminated food, water, surfaces, and close contact with infected individuals.
• Arenaviruses


  • Characterized by their spherical shape, enveloped structure, and T-shaped glycoprotein spikes on their surface
  • There are twenty-nine serotypes of arenaviruses known to date
  • Primarily transmitted to humans through contact with or inhalation of aerosols containing infected rodent excrement
• Lymphocytic Choriomeningitis Virus (LCMV)


  • LCMV infection can cause aseptic meningitis, an inflammation of the membranes surrounding the brain and spinal cord
  • Symptoms may include fever, headache, stiff neck, nausea, vomiting, and sensitivity to light
  • In severe cases, LCMV infection can lead to encephalitis (inflammation of the brain) or meningoencephalitis
• Lassa Fever Virus


  • Lassa fever is a viral hemorrhagic fever caused by Lassa virus
  • Endemic in parts of West Africa, particularly in Sierra Leone, Liberia, Guinea, and Nigeria
  • Lassa fever can cause a range of symptoms, from mild fever and malaise to severe hemorrhagic manifestations, shock, and death
  • Diagnosis of Lassa fever is typically confirmed through serological tests or reverse transcription-polymerase chain reaction (RT-PCR) to detect viral RNA
• Arenaviruses are a significant public health concern in regions where they are endemic, particularly due to their potential to cause severe and often fatal diseases such as Lassa fever. Early diagnosis, supportive care, and appropriate infection control measures are crucial for managing cases of arenavirus infection and preventing transmission to others.
• Bunyaviruses


  • Characterized by their enveloped structure and segmented, single-stranded RNA genome
  • Genome consists of three single-stranded RNA segments enclosed in a helical nucleocapsid, encoding for various viral proteins necessary for replication and infection
  • Primarily transmitted by arthropod vectors such as mosquitoes and ticks, but some bunyaviruses, such as hantaviruses, are transmitted through exposure to rodent excreta
  • The Bunyaviridae family includes approximately 300 total members, many of which are associated with arthropod-borne diseases